STARTS BUT SHUTS OFF IN SECONDS? LOST THE IGNITION KEY AND BROKE THE STEERING LOCK TO START THE ENGINE. 1999 CHEVY BLAZER.

Try to reset security manually. Make sure battery is good. Insert key into ignition turn to on position (make sure to "bump starter"every time you turn to on position). Leave in ignition for 11 minutes. Security light should go off before proceeding to next step. Turn key to off position for 30 seconds. Then turn back to on position for 11 minutes. Then turn to off position for another 30seconds. Then turn to on position for another 11 minutes. Then turn to off position for 30 seconds. Turn key to on position again for 30 seconds. Start engine. That should work if every thing is compatible

The most common repair is to replace the ignition lock cylinder due to broken wires inside the steering column. Most common problems related to the Passlock family involve the Passlock sensor. The sensor is part of the ignition lock cylinder on Passlock I and Passlock II systems. ( Where the key goes ), Good-Day!

You may be having an intermittent failure with the fuel pressure regulator - checking the fuel pressure when the truck won't start may pinpoint this problem. If the pressure looks OK, this same problem can be caused by the ignition system as well (ignition coil or control module).

if it just shuts off, try the auto shutoff relay box..it may be loosing connection with the rest of the harness..

Fixing stuck key in your gmc envoy same as a blazer !
Ignition Lock Cylinder Control Actuator
If the vehicle is equipped with a floor mounted console gear shifter, it has a ignition lock cylinder control actuator system in the steering column as an added safety feature. The ignition lock cylinder control actuators purpose is to prevent the steering wheel from being locked when the transmission is in gear and the vehicle may still be moving. The column ignition lock system consists of a ignition lock cylinder control acutator, and a park position switch that is located in the A/T shift lock control switch. The ignition lock cylinder control acutator contains a pin that is spring loaded out to mechanically prevent the ignition key cylinder from being turned to the lock position when vehicle transmission is not in the Park position. If vehicle power is lost, and/or the transmission is not in the Park position the operator will not be able to turn the ignition key to the lock position and will not be able to remove the ignition key from the column.

No your ignition is a different lock but it could be keyed the same by a locksmith or possibly one could be ordered to match it from the factory based on your vehicle identification number.

it sounds like you have fuel starvation. try cleaning out your carbourator

You wrote ignition switch/lock cylinder. Which part did you replace? The ignition switch or the ignition lock cylinder? The electrical ignition switch is what is bad.

1997 blazer put car in park shut it off but, key won't turn far enough back to come out

I don't think the key and tumbler is your problem at all. The switch is down on your steering column. It's either loose and sliding around when the rod pulls, or it's wrecked. They can cause all kinds of problems. Just drop your steering column and take a look.